This invention relates to a method for abrading fabric garments in both commercial and household-type washing machines. More particularly the method of the invention relates to what is commonly known in the laundry industry as "stone washing."
Current methods of stone washing fall into two general categories. The first is a method which utilizes large pumice stones (2 inches to 4 inches in diameter and larger) in the washing process. In the pumice stone method, large pumice stones are placed within the washing cylinder of a washing machine along with the garments during the wash cycle. Numerous significant disadvantages exist with the pumice stone method. First the stones bang against the inside of the cylinder during the agitation step, causing damage to the inside of the cylinder, and resulting in breakage of the stones. When the stones strike the inside of the cylinder, garments are often pinched between the cylinder and the stone, producing holes and tears in the garments. When the stones break, sharp edges are formed on the stones and these contact the garment, also resulting in damage to the fabric. After each washing cycle, the stones must be laboriously removed from the cylinder as the garments are prepared for rinsing, removal and/or drying. Alternatively, the garments must be removed from the cylinder while leaving the stones in the cylinder. In either of the two aforementioned circumstances, laundry operators have to handle the sharp stones. The second existing method of stone washing garments utilizes a method whereby volcanic rock is used to actually abrade the cylinder in the washing machine. Garments are then put into the machine having this specially abraded cylinder, and the rough surface of the cylinder works on the garment, achieving the desired abrasion. The particular disadvantages with the abraded cylinder method relate to the need for repeated resurfacing of the cylinder after a number of washes. The abraded cylinder method also has a disadvantage in that it takes considerable time and energy to achieve adequate abrasion on the garment.
An existing problem with stone washing done with the current methods relates to "streaking" of the garments. In the normal circumstance, new fabric garments are received at the laundry after being folded and shipped by the manufacturer or customer. The weight of the garments lying one on top of the other causes the garments to have creases and folds prior to stone washing. When the garments are placed in the washing machines for the soaking cycle, the creased and folded garments rub against the inside of the cylinder wall, causing streaks where the creases or folds exist. Even though, in the pumice stone method, the stones may not be placed within the washing cylinder until after the soak cycle, laundries utilizing the pumice stone method have still experienced the streaking problem because of the abrasions on the inside of the cylinder as a result of the stones banging on the inner walls. With the abraded cylinder method, streaking can be eliminated by soaking the garments in non-abraded cylinders and then placing the soaked and softened garments into the specially abraded cylinders for the washing cycle. This additional step is labor and equipment cost intensive, and in practice is not done because of such factors.
Thus, obtaining uniform abrasion has not proved successful with existing methods. Because the garments must actually contact the cylinder walls in the abraded cylinder method, or contact the outer surface of the pumice stone in the pumice stone method, considerable time is required to achieve less than satisfactorily uniform abrasion.